AND PERSONALITY 



The attacking animals, the Carnivora, such as the lion, 

 the leopard, the cheetah, the wild dog, the wolf, the fox, 

 the coyote, the mountain lion, have a light covering of hair. 

 All these animals maintain their protoplasm, whether in a 

 hot or cold climate, at a safe temperature level. 



Some animals, such as the elephant and the rhinoceros, 

 which are usually considered to be hairless, have a skin 

 that is actually a semisolid mass of hair or wool. It is as if 

 nature produced the compounds of which hair is made and 

 then ensheathed the animals in a layer of plastics of hair 

 rather than in hair itself. This great envelope of plastic 

 hair has the same property of being as low a conductor of 

 heat as hair. So, in reality, the elephant, the rhinoceros, 

 and the hippopotamus are encased in a comparatively 

 heatproof layer of plastic hair. These animals increase their 

 heat loss by spraying water over their backs, as in the 

 case of the elephant, or by seeking the damp of the cool 

 jungle and wallowing in the swamps and streams. 



It would appear, then, that heatstroke is a fundamental 

 fact in determining the intelligence, power, and personality 

 of animals and that the size of the brain, the heart and the 

 blood volume, the thyroid gland, and the adrenal glands is 

 related to the surface area of the animal and to its mass. 



It might be suggested that instead of the size of the 

 brain, the heart, the thyroid gland, and the adrenal- 

 sympathetic system being limited by the tolerance of proto- 

 plasm to heat, the size of the energy system of a given 

 animal is related to the supply of oxygen to the muscles. 

 In support of this suggestion might be cited the so-called 

 "oxygen deficit" that occurs as the result of vigorous 

 muscular exercise, such as running and fighting. 



We must, however, take into account two facts, (i) Each 

 fiber of the muscle of the heart, which has the highest 

 metabolism among the muscles of the body, is supplied 

 with capillaries in close apposition to it so as to prevent 

 oxygen deficit in that fiber as it performs its maximum 



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